Method for automatically preparing a working plan

ABSTRACT

A method for automatically preparing a working plan for producing a product having several components. The method involves the following steps: a) providing a product data model of the product, in which each component is described by a partial data set containing a classification characteristic; b) preparing a database, whereby the data sets contained therein are divided into classes according to the classification characteristic, whereby each class contains one or more selection rules, whereby a manufacturing partial process provided with an index is assigned to each selection rule, and each manufacturing partial process contains one or more working cycles; c) automatically selecting the class applying to the component by using the classification characteristic; d) automatically selecting a manufacturing partial process suited for producing the component by using the selection rule; e) automatically establishing the sequence of the manufacturing partial processes by using the respective index.

The invention relates to a method for automatically preparing a workingplan for producing a product comprising a number of components, forexample a wiring harness. It also relates to a device for carrying outthe method.

Most products comprise a multiplicity of components. For example, thewiring harness of a motor vehicle comprises a multiplicity of cablesprovided with different color codes. Attached at the ends of the cablesthere may be connectors of various forms, which for their part are inturn formed by component parts, such as a contact shoe and an insulationenclosing the contact shoe. For each component it is necessary toestablish the type and sequence of the respective working operations.The result is an element-specific partial manufacturing process.Finally, it is necessary to establish the sequence of the partialmanufacturing processes.

It is generally known to prepare a working plan for producing a product.The working plan describes the type and sequence of the individualpartial manufacturing processes required for producing the product. Theselection of the partial manufacturing processes or working operationsdepends on the available resources, for example machines. The workingplan has the aim of specifying a manufacturing process for the productto be produced which saves as much as possible in terms of cost andtime.

At present, a working plan is prepared manually with the aid of computerprograms. In this case it is necessary to produce a data set which isspecific to the respective computer program and describes thecharacteristics of the product to be produced program-specifically. Thisoperation requires experienced, technically trained personnel; it isconsequently time-consuming and costly. The working plans prepared usingconventional computer-aided methods are often imprecise. As a result,the production costs for the product increase.

A method for planning the manufacture of a set of dies for a pressingmachine is known from DE 198 07 343. In this case, data of the productto be manufactured will be compared with data of previously plannedproducts. Depending on the similarity of the data compared, suitablemanufacturing steps are then selected. The method has the disadvantagethat the same manufacturing means always have to be kept available. Ifthe manufacturing means change, under some circumstances thepredetermined similarity relationships also no longer coincide.

According to the prior art, it is also known to design new products on acomputer using CAD programs. The CAD data sets prepared by means of suchprograms are suitable, for example, for controlling computer-controlledmachines. Using the CAD data sets, it is possible, for producing aprototype, to produce components of the product directly, for example bymachining.

U.S. Pat. No. 5,249,135 describes a computer-aided method of producing acomponent of a product. In this case, the manufacturing steps of acomponent are planned on the basis of a model of the part. The knownmethod is not suitable for automatically preparing a working plan forproducing a product comprising a number of components.

It is an object of the invention to eliminate the disadvantages of theprior art. It is intended in particular to provide a method forselecting and determining the sequence of working operations which canbe carried out simply and at low cost. It is a further aim to lower themanufacturing costs for a product.

This object is achieved by the features of claims 1 and 9. Expedientconfigurations emerge from the features of claims 2 to 8.

According to the invention, a method for automatically preparing aworking plan for producing a product comprising a number of components,for example a wiring harness, is provided with the following steps:

-   -   a) providing a product data model of the product, in which each        component is described by a partial data set containing a        classification characteristic,    -   b) preparing a database, the data sets contained therein being        divided into classes according to the classification        characteristic, each class containing one or more selection        rules, each selection rule being assigned a partial        manufacturing process provided with an index, and each partial        manufacturing process containing one or more working operations,    -   c) automatically selecting the class applying to the component        on the basis of the classification characteristic,    -   d) automatically selecting a partial manufacturing process        suitable for producing the component by means of the selection        rule,    -   e) automatically establishing the sequence of the partial        manufacturing processes on the basis of the respective index.

DEFINITIONS

Working plan: step-by-step description of the manufacturing process fora product. The working plan comprises successive partial manufacturingprocesses.

Product: physical object which comprises a number of components.

CAD data model: data model which has been prepared for designing theproduct by means of a CAD program. The CAD data model comprises partialdata sets which describe the components of the product.

Product data model: data model in which the partial data sets of a CADdata model are assigned characteristics which are relevant for themanufacturing process, i.e. influence the selection of a suitablepartial manufacturing process and/or the calculation of the likelymachining times.

Database: knowledge base; it comprises data sets which respectively forma class. The data sets comprise the selection rule, the possiblemachining steps, the computing specifications for calculating themachining times and the like.

Classification characteristic: characteristic which makes it possible toassign a partial data set to a predetermined class.

Index: ordinal number for establishing the sequence of the partialmanufacturing processes in the working plan.

Partial manufacturing process: sequence of working operations, eachworking operation being assigned a unique key and/or a text, a resourceand the manufacturing time.

The method according to the invention makes it possible to specify anoptimized working plan in a simple and quick manner. The manufacturingcosts for the product can consequently be lowered. By means of themethod according to the invention, working plans for a number ofmanufacturing sites can be quickly prepared and it can be ascertained bycomparison at which of the manufacturing sites the product can beproduced at lowest cost.

The classification characteristic may be a material-specificcharacteristic. A material-specific characteristic is chosen as aclassification characteristic in particular whenever the productconsists of different materials. If the product is formed from onematerial which can be machined by one and the same machine, othercharacteristics, for example geometrical characteristics, may also beused as classification characteristics.

Geometrical data and characteristics contained in the partial data setare advantageously processed by means of the selection rule. This makesit possible to calculate particularly exactly in advance the workingtime to be expended for the respective working operation.

The partial manufacturing processes stored in the database areexpediently checked one after the other hierarchically with decreasingcomplexity for the selection of a suitable partial manufacturingprocess.

This reduces the computing time and makes the method particularlyefficient.

Each partial manufacturing process may comprise a number of workingoperations and the expenditure of time for the working operation can becalculated by means of data or a computing specification predeterminedfor each of the working operations.

According to a further configurational feature, each partialmanufacturing process is assigned at least one working means and a text.A working plan showing the sequence of the ascertained partialmanufacturing processes, the working means required for the partialmanufacturing processes and the expenditure of time required for therespective partial manufacturing process can be output as the result ona screen, as a file or in printed form.

It is particularly advantageous for transactions which simulate themanual preparation of a working plan with the aid of conventionalbusiness management software to be derived automatically from theascertained partial manufacturing processes.

Conventional business management software is understood as meaningproduct-planning and control systems. Such systems or computer softwareis sold the company SAP AG, for example. To make it easier for the userof such systems, a possibility for comparison is provided. There is noneed for complex retraining schedules or instructions to operate themethod according to the invention.

The invention also relates to a device for data processing, set up forcarrying out the method according to the invention. It may be aconventional personal computer, which is provided with a program forautomatically carrying out the method according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is explained in more detailbelow on the basis of the drawing, in which:

FIG. 1 shows a first flow diagram and

FIG. 2 shows a second flow diagram.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The flow diagrams shown in FIGS. 1 and 2 describe by way of example theautomatic preparation of a working plan for producing a motor-vehiclewiring harness.

A product data model of a motor-vehicle wiring harness is provided. Theproduct data model contains a partial data set for each component, eachpartial data set being assigned characteristics. The partial data setsare sequentially read out and processed with the assignedcharacteristics.

For this purpose, it has proven to be expedient in the present exampleto prepare a database divided into the following classes:

-   lines-   special lines-   connectors-   bought-in parts or bought parts-   splices-   grommets-   seals (=Seal) and the like.

The assignment of the selected partial data set to one of the classestakes place here on the basis of a machining-specific characteristic.The class “lines” contain, for example, as a machining-specificcharacteristic the characteristic “cutting”. The selection between theclasses “lines” and “special lines” is carried out by means of a furthercharacteristic, for example “resistance” or “diameter”.

Subsequently, the selection rules assigned to the respective class arecompared with the partial data set. It is checked whether or not theselection rule is satisfied by the partial data set. If the selectionrule is not satisfied, the next—more simply structured—selection rule ischecked. As soon as a selection rule which the partial data setsatisfies has been found, the associated sequence of working operationsis selected. Then, the working time required for a working operation iscalculated for each operation by means of the geometrical data containedin the partial data set. In this case, recourse is made to predeterminedcomputing specifications for each working means or each resource. Thecomputing specifications may be, in the simplest case, a constant, aformula or a table.

A partial manufacturing process broken down into individual workingoperations is output as the result. In this case, the working meansrespectively to be used and the required working time are specified.

All the partial manufacturing processes required for producing theproduct are ascertained one after the other. The partial manufacturingprocesses are provided with an index. Finally, an ordering of thepartial manufacturing processes is performed on the basis of the index.The ordered partial manufacturing processes produce the working plan.

In FIG. 2, the selection of a partial manufacturing process is shownonce again in detail. The assignment to a class, here the class “C”,takes place on the basis of a characteristic contained in the productdata model, which here comprises “name”, “component class”, “geometrydescription” and “attributes” (step a). Subsequently, the selectionrules C1, C2, C3, etc. associated with the class are checked (step b).In the actual example, the selection rule C4 is satisfied for thepartial data set checked. This selection rule is assigned a partialmanufacturing process with four working operations. The manufacturingtime is then calculated for each working operation on the basis of acomputing specification stored for it.

The working operations, the resource to be used and the computingspecification are represented once again in detail in the table at thebottom left in FIG. 2. It is evident that the working operation No. 1concerns the activity “cutting special line”, with resource No. “105”being used. For the operation of cutting, a constant “0.25” is providedas the computing specification for calculating the required workingtime.

1. A method for automatically preparing a working plan for producing aproduct comprising a number of components, with the following steps: a)providing a product data model of the product, in which each componentis described by a partial data set containing a classificationcharacteristic, b) preparing a database, data sets contained thereinbeing divided into classes according to a classification characteristic,each class containing one or more selection rules, each selection rulebeing assigned a partial manufacturing process provided with an index,and each partial manufacturing process containing one or more workingoperations, c) automatically selecting a class applying to a componenton a basis of the classification characteristic associated with thecomponent, d) automatically selecting a partial manufacturing processsuitable for producing a component by means of a selection rule, e)automatically establishing a sequence of the partial manufacturingprocesses on the basis of the respective indexes.
 2. The method asclaimed in claim 1, wherein the classification characteristic is amaterial-specific characteristic.
 3. The method as claimed in claim 1,wherein geometrical data and characteristics contained in a partial dataset are processed by a selection rule.
 4. The method as claimed in claim1, wherein partial manufacturing processes stored in the database arechecked one after the other hierarchically with decreasing complexityfor selection of a suitable partial manufacturing process.
 5. The methodas claimed in claim 1, wherein each partial manufacturing processcomprises a number of manufacturing steps and an expenditure of time fora working step is calculated by means of data or a computingspecification predetermined for each of the working steps.
 6. The methodas claimed in claim 1, wherein each partial manufacturing process isassigned at least one working means and a text.
 7. The method as claimedin claim 1, wherein it is possible for a working plan showing thesequence of the partial manufacturing processes, working means requiredfor the partial manufacturing processes, and an expenditure of timerequired for the respective partial manufacturing process to be outputas a result on a screen, as a file or in printed form.
 8. The method asclaimed in claim 1, wherein transactions which simulate manualpreparation of a working plan are derived automatically from ascertainedpartial manufacturing processes.
 9. A device for data processing,wherein said device is adapted to carry out the method according toclaim 1.